Chinchillas have 20 000 hairs per square centimetre (one eighth of an inch square), giving them the densest fur of any land mammal. Chinchillas bathe in dust to remove dirt and oils from their fur, and shed hair throughout the year to keep their coat in top condition. Chinchillas need thick fur to protect against fungal infection and parasites, and if their coat becomes infested they will chew their fur to relieve the itching.
There is a mammal with more densely packed fur than the chinchilla, but it doesn’t live on land. The sea otter has 165 000 hairs per square centimetre (one eighth of an inch square), making its fur completely waterproof. The sea otter never needs to visit land throughout its entire life because it never needs to dry out. Even when completely submerged, a sea otter’s skin stays bone dry.
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